Thickness effects on the physical properties of b-FeSe thin films

M. V. ALE CRIVILLERO; M.L. AMIGÓ; G. NIEVA; N. HABERKORN; H. TROIANI; L. PATRONE; P. GRANEL; F. GOLMAR; J. GUIMPEL

Simposio; XXIII Simposio Latinoamericano de Física del estado Sólido; 2018

The exploration of new emergent phenomena and exotic matter states is an active area in condensed matter physics. These studies require samples of veryhigh quality, which involves characterizing and controlling properties at microscopic scales maintaining homogeneity macroscopically. In this work, we studied thickness effects in the properties of -FeSe grown bysputtering. We report a superconductor-insulator transition by reducing the thickness, for lms in dierent types of substrates and in a wide range of growth temperature.In the literature, there are similar reports in epitaxial films of b-FeSe, which have been interpreted in terms of a possible continuous quantum phase transitioninduced by disorder [1; 2]. In our samples, as the thickness decreases the evolution of the structural and magnetic properties is not trivial, implying that the scheme of induction of disorder is inappropriate.The non-superconducting and insulating samples growth by sputtering present an epitaxial nature. The tetragonal structure and the magnetic order presentin this samples suggest the possibility that these films are of the -Fe4Se5 phase [3], recently proposed as the non-superconducting parent of FeSe.[1] R. Schneider, A. Zaitsev, D. Fuchs et al.; Phys. Rev. Lett. 108, 257003 (2012)[2] R. Schneider, A. Zaitsev, D. Fuchs, et al.; Lett.Supercond. Sci. Technol. 26, 055014 (2013)[3] T. K. Chen, C. Chang, H. Chang et al.; PNAS 111, 63 (2014)